A water pump for a vehicle circulates a coolant through an engine, a heater, etc. for cooling the engine and heating an inside of the vehicle. The coolant in the water pump recirculates after discharged from the water pump and exchanging heat with the engine, the heater, a radiator, or the like.
The water pump is classified into a mechanical water pump and an electric water pump.
The mechanical water pump operates according to rotation of a crankshaft, i.e., rotation of an engine revolutions per minute (RPM) by being connected with a pulley fixed to the crankshaft of the engine. Therefore, a flow rate of the coolant discharged from the mechanical water pump is determined according to the engine RPM.
Here, the flow rate of the coolant necessary for the heater, the radiator, etc. is determined without relation to the engine RPM. In a low engine speed region, since the heater and the radiator cannot operate normally, the engine speed needs to be increased for a normal operation of the heater and the radiator, thus increasing fuel consumption.
The electric water pump operates by a motor controlled through a controller. Therefore, the electric water pump can determine the flow rate of the coolant, regardless of the engine RPM.
However, waterproof function is required for components used in an electric water pump to improve performance and durability of the electric water pump.
The demand for the electric water pump has been increasing. Accordingly, technologies for improving performance and durability of the electric water pump have been developing.
The electric water pump requires a separate pump driver to control an electric motor, and the pump driver is assembled integrally with the electric water pump as a printed circuit board (PCB) in which electrical elements of a microprocessor, a condenser, a resistor, a switch, etc. are integrated.
The PCB is mounted in a pump driver room which is formed at a rear or side portion of the electric water pump. The pump driver room is prevented from water flowing therein by having a sealed structure.
In general, when there is a high load during driving due to a high load of the electric motor, temperature of the PCB also increases.
In addition, since high temperature of about 150 degrees centigrade is maintained in a periphery of the engine on which the electric water pump is mounted, temperature of the pump driver room and the PCB of the electric water pump is high.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.